Even if the U.S. ceases to burn coal, shuts down a quarter of its existing nuclear reactors, and trims its use of natural gas by 2050, the increased reliance on wind, solar and other renewables will not result in a less reliable electricity grid, states a new report by Synapse Energy Economics Inc., conducted for the nonprofit Civil Society Institute (CSI).

The study finds that in a 2050 scenario with a heavy reliance on renewables, regional electricity generation supply could meet or exceed demand in 99.4% of hours, with load being met without imports from other regions and without turning to reserve storage. In addition, surplus power would be available to export in 8.6% of all hours, providing an ample safety net where needed from one region of the U.S. to the next.

"This study shows that the U.S. electricity grid could integrate and balance many times the current level of renewables with no additional reliability issues," says Grant Smith, senior energy analyst of the Civil Society Institute.

"Recent improvements in both renewable technologies themselves and in the technologies that are used to control and balance the grid have been proceeding at a rapid pace, and the incentives and rewards for success in this area continue to drive substantial progress," he says.

In 2011, Synapse prepared a study for the Civil Society Institute that introduced a "Transition Scenario" in which the U.S. retires all of its coal plants and a quarter of its nuclear plants by 2050, moving instead toward a power system based on energy efficiency and renewable energy. The Transition Scenario included large amounts of renewable energy resources with variable output, such as wind and solar.

The new 2013 study explores the extent to which the Transition Scenario's resource mixes for 2030 and 2050 are capable of meeting projected load for each of the 10 studied regions not just during peak demand conditions, but in every hour of every season of the year.

Months after the U.S. Environmental Protection Agency released its Clean Power Plan, which will create new regulations for existing power plants, the agency says it has received loads of feedback to consider.